Almost every tank containing liquids needs a vent of some sort to allow air to escape as liquids are added, or to reenter to replace liquids being drawn out, as well as to allow the escape of fumes or gasses. On a boat, and particularly in regard to gasoline tanks, where the vapors are explosive, these vents must be outside the hull. This poses special problems, since any vent to the outside of the hull must be exposed to the elements of the weather, and especially to rain and spray, which, if it might enter the vent, could be quite damaging to the fuel--and ultimately the engine--or contaminate whatever is in the tank.
The more typical of the existing tank vents include elbows that may have holes for screening and ventilation, but are quite vulnerable to wave action or spray. Other pipes, with or without valves, will perform similar functions both with similar problems. A one-way valve could prevent most contaminants from getting in, but it could also block the flow of air in that direction, which would inhibit one of the functions of the vent, and could be critical.
The vent must not be unattractive, and it must not project too far from the outside of the hull. It must be strong enough to stand occasional physical abuse, and should be easily removable for cleaning, repair, or replacement. It must also have a screening effect to keep bugs, that would not be good for the fuel or the engine, out of the gas tank, or any other tank.
It is therefore an object of this invention to provide a vent that extends through the side of a hull in a simple and secure manner, but also includes a unique combination of baffles to provide protection against rain and spray.